How do I make material like emission but not bloom?
Is this what you're looking for?

I think Bloom is a post-render, whole-frame effect, and some kind of layering would be required to have some objects bloom, and others not, at the same intensity.

As an expansion on the above, BSDFs are closures, meaning they're programs waiting to be run later, which can be modified with various node operators but not read from in your material shader. (It helps us stay renderer-agnostic in our materials.) Bloom is a sort of post-processing effect, and involves ray tracing the light from surrounding geometry; but if you're looking for straight-up color and don't care about lighting, just hand it the color (or texture) directly and it will bypass light calculations entirely.